PHOTO: Kendra Wilkinson shows her positive pregnancy test result in a photo she tweeted on Oct. 31, 2013.

"He's that mature to be able to look and see his friends having little siblings and he's able to look up at me and be, 'Momma, I want a baby brother,'" she said. "He doesn't know where it comes from, so he thinks we just go buy one from the store, so I tell him 'Just be patient, you'll get one soon.'"